True Number of Gallons

[meathead]

Hello everyone,
I have another very basic question for you:
When a tank is sold as a "75-gallon tank", is that before you add sand and live rock? I believe so, but I would like to hear it from someone else.
If so, how much water do you think is displaced by 2" of sand and approx 60 lbs of rock?
I know water changes don't have to be exact, but I'm just trying to narrow it down a bit.
Thanks all

 

[rcoultas]

You are correct in that the volume is stated by it's empty cubic capacity. The displacement by the sand and rock as you stated is approximately 13 gallons leaving you volume at 62 ga. This is assuming your tank is 48" x 18"

 

[big]

Try this link. I do not think SWF will mind the link . You can calculate subsrate odd sizes (Bows Etc) and more............
http://uk.geocities.com/dazasfish/

 

[vapd3129]

Yes, a 75 gallon tank would be 75 gallons with only water and probably filled to the very top.

 

[big]

Yep my 72 with the rock and substrate holds only 50 gallons of water...

 

[vapd3129]

I wonder how much actual water is in my 29g with 35 lbs. of LR and 20 LBS of LS? Probably17 gallons. Well, look at it this way. Makes hitting that 20% monthly water change that much easier.